The request was made in a diplomatic note on 25 June; 16 days later Guzmán escaped the Altiplano prison through a mile-long tunnel which opened into his cell’s shower.

It was the kingpin’s second escape from a high-security prison, and the failure to extradite him after his recapture in 2014 [2] has been fiercely criticised by opponents of President Enrique Peña Nieto.

Guzmán is wanted by US authorities for a variety of criminal charges including money laundering and cocaine smuggling, but Mexico refused to extradite him.

At the time, the then attorney general, Jesús Murillo Karam, told the Associated Press that Guzmán would not be sent to the US until he had served time for all his crimes in Mexico – in “about 300 or 400 years”.

Documents leaked to the AP show that the US Drug Enforcement Administration first received reports that Guzmán intended to escape again about a month after his recapture [3].

But US and Mexican authorities have attempted to play down reports that Guzmán’s escape has created tensions between the two countries [4].

The interior minister, Miguel Ángel Osorio Chong, dismissed reports that his government had rejected US support in the hunt for the fugitive cartel boss, telling reporters: “We have been working together in a coordinated way from the start. The objectives are clear: to recapture this criminal and punish everybody who helped him.”

Mexican authorities have established checkpoints on major highways around the country, distributed 100,000 photos of Guzmán to toll booths and put 10,000 agents from various components of the Mexican federal police on high alert since the escape. DEA and FBI officials have met with officials in Mexico City.

On Friday a senior DEA official expressed confidence that the fugitive cartel boss would soon be recaptured. “I really do think we’ve got him on the run, he’s looking over his shoulder,” operations chief Jack Riley told the AP. “We are going to make it as hard on him as possible.”

The DEA’s former head of international operations Mike Vigil said that the escape would not seriously affect bilateral cooperation on drug issues. “We have to work with Mexico,” he told the Guardian. “We can’t just throw up our hands, pick up our basketball and go home.”